Computer and Expandable Power Supply System Thereof

1. An expandable power supply system, comprising: N interface units adapted for being electrically connected with N power supplies and switching the levels of (N−1) control signals according to conductance of the power supplies, wherein N is an integer, N is equal to or more than two; a determination unit electrically connected with the interface units, wherein when the interface units are electrically connected with 1 st to M th power supplies of the N power supplies, the determination unit outputs a start signal when the determination unit receives power reply signals provided by the 1 st to M th power supplies, M is an integer, and 1≦M≦N; and a voltage converting unit enabled according to the start signal to distribute operation voltages provided by the 1 st to M th power supplies by utilizing the control signals to generate a supply voltage.

2. The expandable power supply system according to claim 1 , when a (i+1) th interface unit of the N interface units is electrically connected with a (i+1) th power supply of the M power supplies, the (i+1) th interface unit switches the level of an i th control signal of the control signals from a first level to a second level, M is more than 1, i is an integer, and 1≦i≦(M−1).

3. The expandable power supply system according to claim 2 , wherein the voltage converting unit comprises: a signal generator outputting a plurality of switch signals according to the start signal; N switch modules, wherein each of the N switch modules has an input terminal, an output terminal, and a plurality of control terminals, the input terminals of the switch modules are electrically connected with the interface units, respectively, to receive the operation voltages provided by the power supplies, the output terminals of the switch modules are electrically connected with each other, and the control terminals of the switch modules are used for receiving the switch signals to switch conducting states of the switch modules; (N−1) change-over switches, wherein a j th change-over switch of the change-over switches is electrically connected between the input terminal of a j th switch module of the switch modules and the input terminal of a (j+1) th switch module of the switch modules, and the j th change-over switch is switched to an off state according to a j th control signal at the second level of the control signals, j is an integer, and 1≦j≦(N−1); and a power output device electrically connected with the output terminals of the switch modules to generate the supply voltage according to the conducting states of the switch modules.

4. The expandable power supply system according to claim 3 , wherein each of the switch modules comprises: a first driven switch, wherein a first terminal of the first driven switch is electrically connected with the input terminal of a corresponding switch module, and a second terminal of the first driven switch is electrically connected with the output terminal of the corresponding switch module; and a second driven switch, wherein a first terminal of the second driven switch is electrically connected with the second terminal of the first driven switch, a second terminal of the second driven switch is electrically connected with a grounding voltage, and the first driven switch and the second driven switch are controlled by partial switch signals of the switch signals.

5. The expandable power supply system according to claim 3 , wherein the power output device comprises: an inductor, wherein a first terminal of the inductor is electrically connected with the output terminals of the switch modules, and a second terminal of the inductor is used for outputting the supply voltage; and a capacitor, wherein a first terminal of the capacitor is electrically connected with the second terminal of the inductor, and a second terminal of the capacitor is electrically connected with a grounding voltage.

6. The expandable power supply system according to claim 2 , wherein N equals to two, and the determination unit comprises: an AND gate having a first input terminal and a second input terminal for receiving the power reply signals provided by the 1 st power supply and the 2 nd power supply of the power supplies, and having an output terminal to generate the start signal; and a switch, wherein a first terminal of the switch is electrically connected with the first input terminal of the AND gate, a second terminal of the switch is electrically connected with the output terminal of the AND gate, and the switch is switched to an off state according to the 1 st control signal at the second level.

7. The expandable power supply system according to claim 1 , wherein each of the interface units is composed of a connector.

8. A computer, comprising: a main board; a power manager disposed on the main board; and an expandable power supply system disposed on the main board, wherein the expandable power supply further includes: N interface units adapted for being electrically connected with N power supplies and electrically connected with the power manager, wherein the interface units switch the levels of (N−1) control signals according to conductance between the interface units and the power supplies, and wherein N is equal to or more than two; a determination unit electrically connected with the interface units, wherein when the interface units are electrically connected with 1 st to M th power supplies, the power manager transmits a power start signal to the 1 st to M th power supplies, via the interface units to enable the 1 st to M th power supplies to start to supply power, the determination unit outputs a start signal when the determination unit receives power reply signals provided by the 1 st to M th power supplies, M is an integer, and 1≦M≦N; and a voltage converting unit enabled according to the start signal to utilize the control signals to distribute the operation voltages provided by the l st to M th power supplies to generate a supply voltage needed by the main board.

9. The computer according to claim 8 , wherein when a (i+1) th interface unit of the interface units is electrically connected with a (i+1) th power supply of the power supplies, the (i+1) th interface unit switches the level of an i th control signal of the control signals from a first level to a second level, M is larger than one, i is an integer, and 1≦i≦(M−1).

10. The computer according to claim 9 , wherein the voltage converting unit comprises: a signal generator outputting a plurality of switch signals according to the start signal; N switch modules, wherein each of the N switch modules has an input terminal, an output terminal, and a plurality of control terminals, the input terminals of the switch modules are electrically connected with the interface units, respectively, to receive the operation voltages provided by the power supplies, the output terminals of the switch modules are electrically connected with each other, and the control terminals of the switch modules are used for receiving the switch signals to switch conducting states of the switch modules; (N−1) change-over switches, wherein a j th change-over switch of the change-over switches is electrically connected between the input terminal of a j th switch module of the switch modules and the input terminal of a (j+1) th switch module of the switch modules, and the j th change-over switch is switched to an off state according to a j th control signal at the second level of the control signals, j is an integer, and 1≦j≦(N−1); and a power output device electrically connected with the output terminals of the switch modules to generate the supply voltage according to the conducting states of the switch modules.

11. The computer according to claim 10 , wherein each of the switch modules comprises: a first driven switch, wherein a first terminal of the first driven switch is electrically connected with the input terminal of a corresponding switch module, and a second terminal of the first driven switch is electrically connected with the output terminal of the corresponding switch module; and a second driven switch, wherein a first terminal of the second driven switch is electrically connected with the second terminal of the first driven switch, a second terminal of the second driven switch is electrically connected with a grounding voltage, and the first driven switch and the second driven switch are controlled by partial switch signals of the switch signals.

12. The computer according to claim 10 , wherein the power output device comprises: an inductor, wherein a first terminal of the inductor is electrically connected with the output terminals of the switch modules, and a second terminal of the inductor is used for outputting the supply voltage; and a capacitor, wherein a first terminal of the capacitor is electrically connected with the second terminal of the inductor, and a second terminal of the capacitor is electrically connected with a grounding voltage.

13. The computer according to claim 9 , wherein N equals to two, and the determination unit comprises: an AND gate having a first input terminal and a second input terminal to receive the power reply signals provided by the 1 st power supply and the 2 nd power supply of the power supplies, and having an output terminal to generate the start signal; and a switch, wherein a first terminal of the switch is electrically connected with the first input terminal of the AND gate, a second terminal of the switch is electrically connected with the output terminal of the AND gate, and the switch is switched to the off state according to the 1 st control signal at the second level.

14. The computer according to claim 8 , wherein each of the interface units is composed of a connector.